Highly Enantioselective Catalytic Cross-Dehydrogenative Coupling of N-Carbamoyl Tetrahydroisoquinolines and Terminal Alkynes

The first catalytic asymmetric cross-dehydrogenative coupling of cyclic carbamates and terminal alkynes has been established. The reaction features high enantiocontrol and excellent functional group tolerance and displays a wide range of structurally and electronically diverse carbamates as well as terminal alkynes. N-Acyl hemiaminals were identified as the reactive intermediates through preliminary control experiments. Employing readily removable carbamates as substrates rather than traditionally adopted N-aryl amines allows applications in complex molecule synthesis and therefore advances the CH functionalization strategy to a synthetically useful level.